1. Field of the Invention
This invention relates to novel crystalline aluminosilicates and to methods for their preparation. More particularly, this invention relates to novel crystalline aluminosilicates having unique sorption and catalytic properties, to methods for preparing the same and to organic compound conversion, especially hydrocarbon conversion, therewith.
2. Description of the Prior Art
Zeolitic materials, both natural and synthetic, have been demonstrated in the past to have catalytic capabilities for various types of organic compound conversion, especially hydrocarbon conversion. Certain of these zeolites comprise ordered porous crystalline aluminosilicates having a definite crystalline structure, as determined by X-ray diffraction, within which there are a large number of small cavities which may be interconnected by a series of still smaller channels or pores. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as "molecular sieves" and are utilized in a variety of ways to take advantage of these properties.
These molecular sieves include a wide variety of positive ion-containing crystalline aluminosilicates, both natural and synthetic. Among the synthetic zeolites are those known as A, Y, L, D, R, S, T, Z, E, F, Q, B, X, erionite and offretite. All can be generally described as having a rigid 3-dimensional network of SiO.sub.4 and ALO.sub.4 in which the tetrahedra are cross-linked by the sharing of oxygen atoms whereby the ratio of the total aluminum and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing aluminum is negatively charged and the composition is balanced by the inclusion in the crystal structure of a cation, for example, an alkali metal or an alkaline earth metal cation. Thus, a univalent positive sodium cation balances one negatively charged aluminosilicate tetrahedra. When an alkaline earth metal cation is employed in the crystal structure of an aluminosilicate, it balances two negatively charged aluminosilicate tetrahedra because of its doubly positive valence. The spaces between the tetrahdedra are occupied by molecules of water prior to dehydration.